Conventionally, a mode control waveguide-type laser device as illustrated in FIGS. 9, 10, and 11 has been proposed to realize a laser device capable of oscillating in high luminance (for example, see Patent Literature 1).
FIG. 9 is a side view illustrating a structure of the conventional mode control waveguide-type laser device. FIG. 10 is a cross sectional view taken along the cross section line a-a′ of FIG. 9 as seen from a laser exit side, and FIG. 11 is a cross sectional view taken along the cross section line b-b′ of FIG. 9 as seen from the top face.
In FIGS. 9 to 11, the conventional mode control waveguide-type laser device includes a semiconductor laser 101 for excitation for emitting excited light, a laser medium 105 for emitting laser light, a cladding 104 bonded onto the lower surface of the laser medium 105, and a heat sink 102 bonded with a bonding agent 103 onto the lower surface of the cladding 104.
The laser medium 105 is planar and has a waveguide structure in a thickness direction (y axis) of a cross section perpendicular to an optical axis 106 (z axis) representing a laser oscillation direction, and has a cyclic lens effect in a direction (x axis) perpendicular to the optical axis 106 and the thickness direction.
A total reflection coating that reflects laser light is provided on an end surface 105a on the incident side of the laser medium 105, and an anti-reflection coating that reflects a part of laser light and transmits a part thereof is provided on an end surface 105b on the exit side. These total reflection coating and partial reflection coating are formed by, for example, laminating dielectric thin films.
As illustrated in FIG. 9, when the excitation light exiting from the semiconductor laser 101 enters from the end surface 105a of the laser medium 105, the total reflection coating of the end surface 105a becomes an optical film which transmits the excitation light and reflects the laser light.
Moreover, as illustrated in FIGS. 10 and 11, the heat sink 102 has an extended comb structure parallel to the optical axis 106 (z axis).
The excitation light entering from the end surface 105a of the laser medium 105 is absorbed in the laser medium 105 to generate gain with respect to the laser light inside of the laser medium 105.
The gain generated inside of the laser medium 105 causes the laser light to laser-oscillate between the end surface 105a and the end surface 105b of the laser medium 105 which are perpendicular to the optical axis 106, and a part of the oscillation light is output from the end surface 105b to the outside of a laser resonator.
In the conventional mode control waveguide-type laser device illustrated in FIGS. 9 to 11, when laser power required for the laser device is determined, necessary excitation power is determined.
Moreover, according to a power scale of the determined excitation power, an excitation region of the excitation light in the waveguide width direction (X axis direction) is determined, and further a mutual space of teeth of the extended comb structure of the heat sink 102 is determined depending on the excitation region.